1. Field of the Invention
The present invention relates to telecommunications channel interference suppression, and particularly to a two-path amplify-and-forward relaying method for bandwidth efficient cognitive radios which provides makes use of the inter-relay interference (IRI) between two relay nodes to transmit secondary user (SU) data and cancel this IRI at the primary user (PU) receiver node.
2. Description of the Related Art
A two-path relay scheme has recently been considered as an attractive wireless communication scheme to improve the spectral efficiency and performance of half duplex cooperative networks. The two-path relay scheme consists of a source node S, a destination D and two relay nodes RA and RB. Transmission time slots are divided between the two relays, i.e. while one relay receives the source data the other one relays the previous data received during the previous time slot. Two-path relay scheme needs (N+1) time slots to transmit N data frames from S to D. In order to increase bandwidth efficiency of N/(N+1) and make it close to one, N should be sufficiently large.
In the related art, the two-path relay scheme was used only to relay data from node S to node D using one of the two famous relaying protocols amplify-and-forward (AF) or decode-and forward (DF). Due to the simultaneous transmission from S to relay nodes RA and RB, inter-relay interference (IRI) problem appears and causes system performance degradation. IRI is a problem that remains with this relay scheme.
Thus, a two-path amplify-and-forward relaying method for bandwidth efficient cognitive radiossolving the aforementioned problems is desired.